Tool retainer



March 10, 1970 J. E. cALMusKY 3,499,656

TOOL RETAINER Filed April l1, 1968 2 Sheets-Sheet 2 /N VENTO/Q JOHN E.CALMUSKY United States Patent() 3,499,656 TOOL RETAINER John E.Calmusky, 110 Clark Ave., Kitchener, Ontario, Canada Filed Apr. 11,1968, Ser. No. 720,580 Int. Cl. E21c 3/34 U.S. Cl. 279-191 9 ClaimsABSTRACT OF THE DISCLOSURE To those familiar with the eld of rockdrilling and the operation of other power operated percussive tools itis well known to provide a drill steel retainer which allows freedom ofrotation to the drill steel and a limited amount of freedom for axialmovement of the drill steel while preventing accidental disengagement ofthe drill steel from the rock drill or forcible ejection of the drillsteel from the rock drill during operation thereof. In general suchretaining devices are in the form of a fork having a U-shaped openinglarger than the diameter of the drill steel but smaller than thediameter of a collar on the drill steel. Such a fork is normally mountedso as to be resiliently held in an engaged position while at the sametime being movable by external force into a disengaged position so thatthe drill steel may be changed or removed for inspection and after beingreinserted in the rock drill the above described fork is biased into theformer engaged position to maintain the drill steel in operativeposition within the rock drill.

The use of the fork as a retainer has been satisfactory and meansdevised for maintaining the fork in the engaged and disengaged position,respectively, have served the purpose but have been unsatisfactory byreason ofrequiring a multiplicity of parts and because of too rapidwearing out caused by metal-to-metal contact coupled with severevibratory conditions and further aggravated by dust and other forms ofgrit attendant upon the operation of rock drills and other poweroperated percussive tools.

The retaining device of this invention comprises a fork portion as abovedescribed forming the central portion of a stirrup shaped supportelement having arms, spaced apart and parallel to each other, extendingfrom the forked portion rearwardly along opposite side surfaces of arock drill front head and having in the leg portions Coaxial openings. Asquare shaft or pin is rigidly removably secured in the two openings andextends in spaced relationship through a square or other-wisenoncircular opening extending transversely through the front head of therock drill. Between the square shaft and the square opening a resilientbushing, 'having an internal opening of the same shape as the exteriorof the shaft and an external surface of the same shape as the interiorof the front head transverse opening, fills the space between the shaftand the transverse opening. With a square shaft fitting the formedopening in a resilient bushing and with proper orientation of the squarewith respect to the rearwardly extending arms f the stirrup shapedretainer support element, the formed portion will be held in the engagedposition relative to the collared drill steel. Since the shaft is squareand mounted in a square opening in the resilient bushing, a rotativebiasing force applied to the fork portion of the support element willcause the shaft to rotate within the resilient bushing until after ICCrotation of something more than 45 of rotation the squares will beapproaching normal registration and the support element will snap into anew position rotated from its original position and constrained to stayin this now disengaged position by the action of the resilient materialupon the square shaft. It is therefore an object of this invention toprovide a new and improved steel retaining device which is easy tooperate, long wearing, and comprises a minimum number of relativelysimple parts requiring no highly precise machining and readilyreplaceable without special tools should replacement become necessary.

This and other objects and advantages of this invention will be morereadily apparent upon consideration of the following description anddrawings in which:

FIG. 1 is a top plan view of a rock drill constructed according to theprinciples of this invention;

FIG. 2 is an enlarged fragmentary sectional view taken substantially online 2 2 of FIG. l;

FIG. 3 is a partially sectional view taken substantially on line 3-3 ofFIG. 2;

FIG. 4 is a View similar to FIG. 2 with the components thereof rotatedinto different relative positions, including broken line representationsof still other positions;

FIG. 5 is a fragmentary side elevational view of a portion of the rockdrill of FIG. 1 on the enlarged scale of FIGS. 2 through 4;

FIG. 6 is a view taken substantially on line 6-6 of FIG. 3.

In FIG. 1 there is shown a rock drill of a type well known in the artgenerally indicated at lll and comprising a back head 12 to the left asseen in FIG. l, a body portion 14 and a front head portion 16 to theright as viewed in FIG. l. For purposes of description the direction tothe right in FIGS. l through 5 will be designated as a forward directionWhile the direction to the left will be taken as the rearward directionconsistent with the usage well established in the field of rock drillingmachinery as evidenced by the accepted names of the back head 12 andfront head 16. The back head 12 is provided with an air inlet 18 to beconnected to a source of compressed air (not shown) and suitable valvingto provide compressed air for reciprocation of a hammer piston withinthe body portion 14 for percussively actuating a collared drill steel 20of a type Well known in the art slideably received within an internallypolygonal opening 17 in the front head 16 for percussive andintermittent rotative actuation in a known manner.

The drill steel 20 is an elongated member extending forwardly to form,or be connected to, a suitable drill bit engaging a work surface (notshown) and extends rearwardly within the front head 1-6 a suitabledistance to be percussively acted upon and intermittently rotated by thehammer piston in a well known manner. The drill steel 20 normally has agiven diameter polygonal cross section with a collar portion 21 oflarger diameter formed at a Ipoint intermediate its ends to determinethe depth to which the rearward portion of the drill steel 20 shall beslideably received in the opening 17 for the above described actuation.

The front head 16 is provided with a downwardly extending, generallyrectangular boss portion 22 extending across the front head portion 1-6below the steel receiving opening 17 and having a longitudinal centralaxis A-A contained in a plane normal to the longitudinal central axis ofthe drill steel 20. An opening havingl flat internal surfaces, shown vasthe square opening 24, coaxial with the bo-ss portion 22, extendstherethrough and is provided with a maing bushing, such as the squarebushing 2-6, of readily deformable resilient material such as urethane,soft rubber, neoprene, or the like, having a complementary opening, suchas the square opening 28.

coaxial with the boss portion 22 and extending therethrough. Thematerial of the bushing 26 must be soft and readily deformable buthighly resilient so that after being compressed and displaced (ashereinafter described) it will strongly tend to return to its originalshape and size. Furthermore for best results the bushing 26 is madesomewhat larger than the opening 24 so that the bushing 26 is compressedat installation.

The front head 16 is further provided with a stirrup shaped drill steelretaining member 30 having a transversely extending central porti-on 32,spaced forwardly from the front head 16, and having rearwardly extendingarm portions 34 spaced apart a suicient distance to slideably engage theend portions of the boss 22 and long enough to extend rearwardly beyondthe opening 24 in the boss 22. The central portion 32 of the ret-ainingmember 30 is provided with an inverted U shaped opemng 36 (see FIG. 6)having leg portions 37 spaced apart by a distance somewhat greater thanthe diameter of the drill steel 20 but somewhat less than the diameterof the enlarged collar portion 21 so that the drill steel is free toslide axially within the limits imposed by the legs 37 of the centralportion 32 and the front surface of the front head 16 and is likewisefree to rotate within the opening 36 of the central portion 32.

Each of the arm portions 34 is provided with an opening 38 extendingtherethrough along the common axis A-A and cross bored as -at 41. Anelongated square pin or shaft 40, having a transverse bore 39 in eachend portion normal to the axis A-A, is rigidly removably secured in theopenings 38 in the arm portions 34 as by drive pins 42 engaged withopposite ends of the cross bores 41 and bores 39 in the end portions ofthe shaft 40,v or by any other suitable retaining means rigidly securingthe shaft in the arm portions 34 for rotation therewith.

The shaft 40 is sized to cause some compression of the material ofbushing 26 when inserted in the opening 28 and is thus rmly butresiliently held in a given position relative to the boss portion 22with no metal to metal contact therebetween.

Operation of the retaining means 30 of this invention begins with theretainer and associated members positioned as shown in FIG. 2 with thedrill steel being prevented from accidental disengagement with the rockdrill 10, or forceful ejection therefrom in operation of the rock drill10, in a well known manner by the instrumentality of the legs 37engaging the collar 21 whenever the drill'4 steel is disengaged from thework surface which normally holds the drill steel and prevents it frombeing propelled in the forward direction.

With suitable orientation of the square openings 24 and 28 relative tothe cross bores 39 the retaining means 30 will be resiliently held inthe locking position shown in FIG. 2 until it is desired to remove thedrill steel for sharpening, replacement or other reason. A biasing forcetending to rotate the retaining means 30 in a counterclockwisedirection, as viewed in FIG. 2, will cause the bushing 26 to be deformedprogressively against the tendencly of the bushing 26 to retain itsoriginal shape until the position 30' (shown in solid outline in FIG. 4)is reached after approximately 45 counterclockwise rotation from theoriginal position shown in FIG. 2. At this position indicated -as 30'the opening 28 will be distorted into'the shape 28' shown in FIG. 4 withthe resilience of the bushing 26 providing equally balanced forcestending to return the retaining means 30 to its original lockingposition or to rotate the retaining means 30 further inthecounterclockwise direction to a released position 30" rotated 90counterclockwise from the original position 30. After such 90 rotationthe retaining means 30 will be held in the released position 30 by thetendency of the bushing 26 to remain in its original shape since both ofthe square openings and the square shaft 40 will again be oriented asoriginally shown in FIG. 2. After the drill steel has been removed andreplaced a clockwise biasing force applied to the retaining means 30 inthe position 30" will return it to the position 30 after which a slightfurther motion will cause the retaining means 30 to snap into positionas shown in FIG. 2 with the tendency of the bushing 26 to maintain itsoriginal shape again resiliently but firmly maintaining the retainingmeans 30 in the desired position.

The advantages resident in the retaining means of this invention arisefrom:.

(l) The provision of a completely resilient mounting for the shaft 40relative to the rock drill 10 with no metal-to-metal contact under thesevere vibratory conditions present during operation of the rock drill10 resulting in lower rate of wear and less metal fatigue;

(2) The non-rigid but firmly resiliently biased positioning of thecentral portion 32 with the U-shaped opening extending closely above andalongside the drill steel 20 to prevent accidental disengagement of thedrill steel 20 from the rock drill 10 with the attendant .advantage ofyieldably restraining the drill steel so that should the drill steelstrike the legs 37, the retainer 30 can move in any direction necessaryto relieve stresses which might otherwise be applied to the drill steelif a more solidly mounted retainer were used, as in structures of theprior art, resulting in increased drill steel life;

(3) The very limited number of parts necessary to accomplish the purposeof retaining the steel while resiliently maintaining the retainingmember 30 in the engaged or disengaged positions giving lower productioncosts;

(4) The absence of any requirement for high precision machine work sinceno metal to metal rotating or sliding fits are required again reducingcosts; and

(5) The ease with which the device of this invention can be assembledwithout need for special tools or skills.

It is to be noted that although the openings 24 and 2S as well as theshaft 40, mating therewith, have been described as square in crosssection they are actually shown in the drawings as having cross sectionswhich are squares with clipped corners since this is a shape of openingand shaft more readily produced than a true square and free of sharpcorners either internal or external which would have a stressconcentration effect tending to weaken the material where such cornersoccur. In any case adjacent flats on the shaft must be connected in somemanner that avoids a sharp edge which could cut the resilient bushinginstead of deforming it as desired.

It is further to be noted that although the cross sections of theopenings and lshaft are shown as squares having clipped corners suchopenings and shaft can be made in any non-circular shape as for instancehexagonal or partly round with flat sided portions at a suitable angleto each other. For example, if the openings and shaft each have twoflats defining one ninety degree dihedral angle, respectively, thiswould give a preferred orientation for locking and a released positionafter of rotation, wherein the locking position included matching of allflats, while the released position was maintained by mating only oneflat on the shaft with one fiat in each complementary opening.

A preferred embodiment of the tool retainer of this invention havinghereinbefore been described and shown it is to be realized thatvariations in the size, shape and position of the various parts can bemade without departing from the broad scope of this invention. It istherefore respectfully requested that the invention herein disclosed beinterpreted as broadly as possible and limited only by the claimsappended hereto.

What is claimed is:

1. In a tool retainer for retaining a collard drill steel in apercussive tool driver body, the tool retainer having two arm portionsconnected by a bight portion shaped to partially encompass such acollared drill steel when in a locked position, portions of said arrnmembers remote from said bight portion being rigidly secured to spacedportions of a shaft transversely disposed with respect to said collareddrill steel and rotatably mounted in an opening in said body forrotation of said tool retainer between locked and unlocked positions,the improvement comprising: said shaft having at least one flatperipheral surface thereon and said opening having at least one flatsurface therein complementary to said at surfaces of said shaft, and adeformably resilient bushing occupying the space within said opening andexternal to said shaft, said at surfaces respectively opposable to eachother in selected positions of rotation of said shaft with respect tosaid tool driver body to alternatively maintain said tool retainer in adesired one of said locked and unlocked positions.

2. In a tool retainer for retaining a collared drill steel in apercussive tool driver body, the tool retainer having two substantiallyparallel arm portions connected by a bight portion shaped to partiallyencompass such a collared drill steel when in a locked position, the endportions of said arm members, remote from said bight portion, beingrigidly secured to end portions of a shaft transversely disposed withrespect to said collared drill steel and rotatably mounted in an openingin said body for rotation of said tool retainer between locked andunlocked positions, the improvement comprising: said shaft havingsubstantial iiat peripheral surfaces thereon and said opening having atsurfaces therein complementary to said flat surfaces of said shaft and adeformably resilient bushing occupying the space within said opening andexternal to said shaft, said flat surfaces respectively opposable toeach other in selected positions of rotation of said shaft with respectto said tool driver body to maintain said tool retainer in a desired oneof said locked and unlocked positions.

3. A tool retainer as specified in claim 2 wherein said shaft ispolygonal in cross section and said opening has a complementarypolygonal cross section.

4. A tool retainer as specified in claim 2 wherein said shaft is ofsubstantially square cross section for at least a major portion of theshaft length and said deformable bushing is formed with a hollowsubstantially square cross section throughout the length thereof.

5. A tool retainer as specified in claim 4 wherein said shaft and saidopening are sized to cause substantial compression of said bushing whenassembled in coaxial and axially overlapping relationship.

6. A tool retainer as specified in claim 4 wherein said shaft endportions have cross bores and said arm end portions are removablysecured to said shaft end portions by drive pin means received in saidcross bores.

7. A tool retainer as specied in claim 2 wherein said shaft has at leasttwo of said iiat surfaces thereon forming a dihedral angle ofapproximately 8. A tool retainer as speciiied in claim 7 whereinadjacent ones of said at least two ilat surfaces are connected by asubstantially planar surface forming obtuse angles with both of saidadjacent surfaces.

9. A tool retainer as specified in claim 7 wherein adjacent ones of saidat least two flat surfaces cooperating with flat surfaces in saidopening determine at least two preferred positions of said tool retainerrelative to said tool driver body with an angle of approximately 90between said preferred positions.

References Cited UNITED STATES PATENTS 7/1938 Curtis 279-19.l

3/l950 Lear 279--19.l

